Distribution of extracellular matrix glycoproteins in the human mesonephros

Cyclin D1 in human neuroblastic tumors recapitulates its developmental expression: An immunohistochemical study

The protein cyclin D1 (CD1), which belongs to a family of proteins functioning as regulators of CDKs (cyclin-dependent kinases) throughout the cell cycle, has been immunohistochemically detected in a wide variety of human malignant tumors. The aim of the present study was to investigate immunohistochemically the expression and distribution of CD1 in the developing human peripheral sympathetic nervous system (PSNS) and in childhood peripheral neuroblastic tumors (neuroblastomas, ganglioneuroblastomas, and ganglioneuromas). The above mentioned fetal and neoplastic tissues represent an in vivo model in which undifferentiated neuroblastic cells undergo ganglion cell differentiation. During development, a strong nuclear expression of CD1 was restricted to neuroblasts, disappearing progressively from the maturing ganglion cells with increasing gestational age. In neoplastic tissues, CD1 immunoreactivity was restricted to neuroblastic cell component of all neuroblastomas and ganglioneuroblastomas, whereas it was absent or only focally detectable in maturing/mature ganglion cell component of differentiating neuroblastomas, ganglioneuroblastomas, and ganglioneuromas. We conclude that CD1 is a reliable marker, which can be used routinely to stain neuroblastic cells in both developing and neoplastic tissues. Furthermore, our results indicate that CD1 expression in childhood peripheral neuroblastic tumors recapitulates the changes during normal development of PSNS, as previously reported for Bcl-2 oncoprotein, c-ErbB2, insulin-like growth factor 2, β-2-microglobulin, and cathepsin D. This is consistent with the current view that childhood peripheral neuroblastic tumors exhibit gene expression profiles mirroring those occurring during PSNS development.

Wilms' tumor 1 (WT1) protein expression in human developing tissues

Several genes playing crucial roles in human development often reproduce a key role also during the onset and progression of malignant tumors. WT1, a transcription factor expressed with a dynamic pattern during human development, has either oncogenic or suppressor tumor properties. A detailed analysis of the immunohistochemical profile of WT1 protein in human developmental tissues could be exploitable as the rational for better understanding its role in cancerogenesis and planning innovative WT1-based therapeutic approaches. This review focuses on the dynamic immunohistochemical expression and distribution of WT1 protein during human ontogenesis, providing illustrations and discussion on the most relevant findings. The possibility that WT1 nuclear/cytoplasmic expression in some tumors mirrors its normal developmental regulation will be emphasized.

Oncofetal expression of Wilms' tumor 1 (WT1) protein in human fetal, adult and neoplastic skeletal muscle tissues

There is increasing evidence that WT1 protein expression is found not only at nuclear, but also at cytoplasmic, level in several developing and neoplastic tissues. In order to better understand the possible role of WT1 protein in human skeletal myogenesis and oncogenesis of rhabdomyosarcoma, we assessed immunohistochemically its comparative expression in a large series of human developing, adult and neoplastic skeletal muscle tissues. The present study shows that WT1 protein is developmentally expressed in the cytoplasm of human myoblasts from the 6 weeks of gestational age. This expression was maintained in the myotubes of developing muscles of the trunk, head, neck, and extremities, while it was down-regulated in fetal skeletal fibers from 20 weeks of gestational age as well as in adult normal skeletal muscle. Notably, WT1 immunostaining disappeared from rhabdomyomas, whereas it was strongly and diffusely re-expressed in all cases (27/27) of embryonal and alveolar rhabdomyosarcoma. The comparative evaluation of the immunohistochemical findings revealed that WT1 cytoplasmic expression in rhabdomyosarcoma may represent an ontogenetic reversal, and this nuclear transcription factor can also be considered an oncofetal protein which can be exploitable as an additional, highly sensitive immunomarker, together with desmin, myogenin and MyoD1, of this tumor. Moreover, our observations support the rationale for the use of WT1 protein-based target therapy in high risk rhabdomyosarcomas in children and adolescents.

Immunohistochemical expression of Wilms' tumor protein (WT1) in developing human epithelial and mesenchymal tissues

The Wilms' tumor (WT1) gene and its protein product are known to exhibit a dynamic expression profile during development and in the adult organism. Apart from a nuclear expression observed in the urogenital system, its precise localization in other developing human tissues is still largely unknown. Accordingly, the aim of this study was to investigate immunohistochemically the temporal and spatial distribution of WT1 in epithelial and mesenchymal developing human tissues from gestational weeks 7-24. For this purpose we used antibodies against the N-terminal of WT1. As might be expected, WT1 nuclear expression was observed in mesonephric/metanephric glomeruli, metanephric blastema, celom-derived membranes (pleura, peritoneum, serosal surfaces) and sex cords. With regard to mesenchymal tissues, a similar nuclear staining was also obtained in the mesenchyme surrounding Müllerian and Wolffian ducts, as well as in the submesothelial mesenchymal cells of all celomatic-derived membranes. The most striking finding was the detection of strong WT1 cytoplasmic immunostaining in developing skeletal and cardiac muscle cells and endothelial cells. The tissue-specific expression of WT1, together with its different nuclear/cytoplasmic localization, both suggest that WT1 protein may have shuttling properties, acting as a protein with complex regulator activity in transcriptional/translation processes during human ontogenesis. The reported cytoplasmic expression of WT1 in human rhabdomyosarcomas and in many vascular tumors strongly suggests an oncofetal expression of this protein. Although not specific, WT1 cytoplasmic expression can be used as a marker of skeletal muscle and endothelial differentiation in an appropriate morphological context.

Migration of human and mouse primordial germ cells and colonization of the developing ovary: An ultrastructural and cytochemical study

This review is an account of the origin and migratory events of primordial germ cells until their settlement in the gonad before sexual differentiation in the human as well as mice. In this context, the morphodynamic characteristics of the migration of the primordial germ cells, the macromolecular characteristics of the extracellular matrix of the migratory pathway, and the factors involved in the germ cell guidance have been analyzed and discussed in the light of recent advances in this field, by means of immunocytochemical procedures. The events prior to gonadal morphogenesis and the origin of the somatic cell content of the human gonadal primordium have been also analyzed. In particular, evidences are presented showing that cells derived from the coelomic epithelium and mesenchyme are at the origin of the somatic components of the gonadal primordium, and that a mesonephric cell contribution to the generation of somatic cell components of the genital ridge in humans should be discarded due to the morphological stability of the different nephric structures during the period preceding the sexual differentiation of the gonad.

[Nephrogenic adenoma of the bladder: metaplasia or embryologic alteration?]

OBJECTIVES

To present a new case of nephrogenic adenoma of the bladder and to review the current concepts on the etiopathogenesis of this lesion.

CLINICAL CASE

Seventy years old female with repetitive haematuria who was diagnosed as having a nephrogenic adenoma of the bladder which was extirpated by cold biopsy forceps. No tumoral relapse was detected after 16 months of follow up.

DISCUSSION

In the light of the present knowledges, the origin of nephrogenic adenoma is a phenomenon of urothelial metaplasia due to a chronic irritative stimulus wich would lead a cellular proliferation with potentialities to originate mesonephric tissues and which starting point could be on not completely involutioned mesonephric cellular rests and/or on de-differentiated mature urothelial cells.

Comparative immunohistochemical analysis of the expression of cytokeratins, vimentin and alpha-smooth muscle actin in human foetal mesonephros and metanephros

The human mesonephros is currently regarded as a simplified version of the foetal metanephros, primarily due to the close morphological resemblance between these two structures. The aim of the present study was to define whether human mesonephric and foetal metanephric nephrons share immunophenotypical traits in their corresponding structures (glomeruli, proximal and distal tubules). For this purpose we first investigated immunohistochemically the overall expression and topographical distribution of cytokeratins 7, 8, 18, 19, and 20, vimentin and alpha-smooth muscle actin in mature mesonephric nephrons and compared the results with those obtained in maturing-stage foetal metanephric nephrons. No expression of cytokeratins 7 and 20 was found. Cytokeratins 8, 18, and 19 and vimentin showed a restricted and basically coincident expression along the different components of both mesonephric and metanephric nephrons. These findings indicate that the intermediate filament protein profile of human mature mesonephric nephrons closely recapitulates that observed in developing metanephros and thereby strengthens the concept that human mesonephros, a transient ontogenic structure, is largely similar to the foetal metanephros. The sole difference between human mesonephros and foetal metanephros was the divergent expression of alpha-smooth muscle actin. This protein exhibited an increasingly accentuated mesangial expression paralleling the morphological maturation of metanephric glomerulus, whereas it was absent from the mesonephric one. This would suggest that the mesangial cells in these two renal structures have a different function during the foetal life.

Immunohistochemical distribution of type VI collagen in developing human kidney

The distribution of type VI collagen was investigated immunohistochemically in the developing human kidney from 15 to 32 weeks gestational age and it was compared with that observed in the normal infantile and adult human kidney. In fetal kidney, type VI collagen was widely distributed as a fibrillar network in the subcapsularly undifferentiated mesenchyme and intertubular interstitium, and as a basement membrane-like structure around the ureteral bud branches, tubules, and collecting ducts. During nephrogenesis, type VI collagen disappeared from the induced mesenchyme close to the tips of ureteral branches, while it formed a distinct basement membrane-like structure around the early stages of nephron differentiation (comma-shaped and S-shaped bodies) and later along Bowman's capsule of capillary loop and maturing glomeruli A strong immureactivity for type VI collagen was also found in the glomerular basement membrane and mesangial areas of capillary loop and maturing glomeruli. In infantile kidney, type VI collagen showed a distribution pattern similar to that observed during the fetal period. In adult human kidney, glomerular basement membrane showed a weak positivity for type VI collagen and the basement membrane-like staining around Bowman's capsule, tubules, and collecting ducts was less evident than in fetal and infantile kidney. Our immunohistochemical findings suggest that type VI collagen is a normal component of the glomerular and extraglomerular extracellular matrix of developing human kidney and that it undergoes changes in the expression during maturation.